Navigation is the science of moving a vehicle or person from one place to another place. More specifically, the science of navigation deals with methods for determining position, course, distance traveled, and of planning steering commands that will result in motion along an intended path from one place to another place. Position is generally determined with regards to a fixed coordinate system, for example, the familiar system of latitude and longitude for terrestrial or nautical navigation. Position fixing methods often make use of navigational aids, whose positions with respect to the navigational coordinate system are known or can be calculated as the basis for determining the location of the vehicle. For example, celestial bodies, e.g., stars, sun, and moon have been used since antiquity to aid sailors in navigating the seas, while a constellation of Global Positioning System (GPS) satellites serves much the same need in a modern, automated fashion. Waypoints, whose positions with respect to the navigational coordinate system are fixed and known, are used to define locations with significance to the navigational problem at hand. For ease of reference, waypoints are generally assigned a waypoint identifier.